Conventionally, methods and apparatuses for measuring various components contained in exhaust gas emitted from an internal combustion of an automobile or the like have been already proposed. For instance, Patent Document 1 discloses a vehicle capable of mounting a NDIR (non-dispersive infrared spectroscopy) gas analyzer, an exhaust gas flowmeter and an arithmetic processing circuit, the NDIR gas analyzer for continuously measuring the HC (hydrocarbon) concentration in exhaust gas flowing through an exhaust tube connected with an engine, the exhaust gas flowmeter continuously measuring a flow rate of the exhaust gas flowing through the exhaust tube, and the arithmetic processing circuit performing arithmetic processing of an output from the NDIR gas analyzer and an output from the exhaust gas flowmeter to continuously calculate the THC (total hydrocarbon) amount in the exhaust gas, thus enabling the measurement of the HC concentration contained in the exhaust gas from the internal combustion of a vehicle such as an automobile traveling on a road. Patent Document 1, however, does not refer to the measurement of particulate matter contained in the exhaust gas.
Patent Document 2 describes a laser measurement apparatus capable of measuring the concentration of suspended particulate matter contained in exhaust gas from an automobile or the like as well as the concentration of carbon dioxide, nitrogen oxides or the like contained in the exhaust gas. In this case, the exhaust gas is introduced into a sampling tube, at one side of which a laser light source is placed and at the other side of which a photoreceiver is placed, so that the applied laser light is scattered by the particulate matter suspended in the exhaust gas, and the thus attenuated laser light is received by the photoreceiver side, thus measuring the concentration of the particulate matter from the attenuation.                Patent Document 1: JP Published Patent Application No. 2004-117259 A        Patent Document 2: JP Published Patent Application No. 2002-48711 A        